﻿#pragma warning(disable: 4996)
#pragma warning(disable: 6031)

#include <stdio.h>

char grade(int n)
{
	char ret = 'E';
	if (n >= 90)
		ret = 'A';
	else if (n >= 80)
		ret = 'B';
	else if (n >= 70)
		ret = 'C';
	else if (n >= 60)
		ret = 'D';
	return ret;
}

void solve(int a) {
	printf("%c\n", grade(a));
}

int main()
{
	freopen("D:/Develop/GitRepos/MOOC/浙江大学/数据结构/201906/DataStructure/M2019秋C入门和进阶练习集/7-17.txt", "r", stdin);
	int a;
	scanf("%d", &a);
	solve(a);
	return 0;
}